NON-STEADY-STATE FLOW BEHAVIOR OF WOOD PULP FIBER SUSPENSIONS

Data are presented for the non-steady-state flow of suspensions of unb leached and bleached kraft pine pulps investigated over a range of flo w rates, acceleration and deceleration rates and fibre concentrations. The friction-loss curves for accelertion and deceleration differ mark edly from the steady state curve resulting in hysteresis. There are si gnificant reductions in pipe friction loss on deceleration and only sm all reductions over a limited range of flow rates when the suspension is under acceleration. The acceleration friction loss curve is above t he steady state curve for the transition flow regime and for plug flow with turbulent annulus. There is potential for reduction in energy in pumping and there are possible applications in the characterization o f dynamic flocculation and related suspension behaviour